Crops for human and animal consumption of many types are well known by their respective growers. Years of experience in the field provide the grower knowledge about a range of conditions that lead to the full spectrum of crop yields and crop quality, and each grower creates a store of knowledge which they can combine with the available measures of those conditions. This disclosure provides a method for indicating the onset of water stress in one or more plants located in a soil the roots of which are within the measurement zone of a soil moisture sensor located in the soil, by determining if there was no recorded water into soil event in the prior 24 hour period of a respective one 24 hour period； determining from representative data whether there are two respective 24 hour periods of the prior seven consecutive 24 hour periods also have evapotranspiration values within a predetermined range； determining from representative data the rate of soil moisture depletion during the plant moisture uptake period within each respective 24 hour period adjusted for drainage； determining whether the rate of soil moisture depletion during the plant moisture uptake period within each respective 24 hour period reduces by a pre-determined level compared to the other of the respective 24 hour period； and indicating the most recent of the respective two 24 hour periods as a period of water stress of the one or more pants.
